One person was killed and others injured when a car rammed into a crowd Monday in the western German city of Mannheim, police said as they asked the public to stay away from the downtown area and remain in their homes. 

Police spokesperson Stefan Wilhelm said a driver drove into a group of people in Paradeplatz, a pedestrianized street in Mannheim, killing one person. He said "several" people were injured but police can't yet specify how many were hurt and how badly they were hurt. 

"We can confirm that one perpetrator was arrested," he said. "We can't yet give information on whether there were further perpetrators." 

Images from the scene showed parts of the downtown area were cordoned off, with a heavy police presence and helicopters hovering above. Police gathered round a badly damaged black car as ambulances lined up outside the cordon.

Paradeplatz, a major square in the downtown area, lies at the end of a pedestrianized street in Mannheim, which has a population of 326,000 and lies 85 kilometres south of Frankfurt. 

Authorities pushed an alert on the Katwarn app telling people in Mannheim to avoid the city's downtown area due to a big police deployment. Katwarn is used by officials to communicate information about major emergencies such as thunderstorms, militant attacks or fires. 

Security has been a key concern in Germany following a string of violent attacks in recent weeks, including deadly car rammings in Magdeburg in December and in Munich last month, as well as a stabbing in Mannheim in May 2024.

Across Germany, many people took a long weekend off to celebrate carnival, including Rose Monday, when several cities hold parades. Mannheim's street parade, however, already took place, on Sunday.